GB762569A - Improvements in or relating to the manufacture of hydrazine hydrobromide - Google Patents

Abstract

<PICT:0762569/III/1> Hydrazine hydrobromide is manufactured in a two stage cyclic process, by absorbing and reacting bromine and ammonia in an aqueous solution of ammonium bromide in a tower contact system and reacting the aqueous ammonium bromide solution, withdrawn from the tower, with hydrazine to form hydrazine hydrobromide and ammonia, the latter being returned to the absorbing and reacting step. Aqueous ammonium bromide solution, ammonia, and liquid bromine enter, through 5, 6, and 3 respectively, the bottom absorption section of tower 1, which is divided into four sections by bubble cap trays. The solution passes to reactor section, where further liquid bromine is added at 4, which is kept flooded and at atmospheric pressure and 60-70 DEG C. by heat exchange. The reacted solution is withdrawn at 10 and part is recycled through 5. The nitrogen evolved in the reaction escapes at 9 after scrubbing with water, entering at 8, in top two sections of tower 1. The remainder of the ammonium bromide solution is passed through 11 to reactor 12, having an agitator into which hydrazine or concentrated (95 per cent) or dilute hydrazine solution, preferably hydrazine hydrate, passes at 13. The contents of the reactor is continuously removed through 14, 15 to vacuum concentrator 16 and returned through 17. Ammonia evolved is returned to tower 1 through 19. The ammonium bromide should be in slight excess and may be passed through an intermediate surge tank to the reactor. An aqueous hydrazine hydrobromide solution (70 per cent) may be withdrawn at 21, or the solution may be passed to vacuum evaporator 23 and the resultant fused water free salt passed to flaker 25 from which solid is recovered. It is stated that the ammonia used in the preparation of the ammonium bromide may be aqueous ammonia.